Sensitisation — When Cues Gain Power
A form of neuroplasticity where repeated exposure makes a system respond more, not less, to a given input.
Sensitisation in dopamine systems means that repeated bursts of dopamine in response to a drug or behaviour make the underlying circuits more responsive over time. In addiction models, this especially affects the “wanting” circuitry in the mesolimbic system: cues associated with the drug come to evoke larger, faster dopamine responses and stronger craving.
This is distinct from tolerance. Tolerance means you need more of the substance to get the same effect (the hedonic/“liking” side weakens). Sensitisation means cues linked to the substance exert stronger motivational pull (the “wanting” side strengthens). The tragic combination: people want more while actually liking the experience less.
Sensitisation also helps explain why relapse can occur after long periods of abstinence: the sensitised circuits haven’t fully reset, so when an old cue shows up — a smell, place, friend, phone notification — the brain’s response can feel unreasonably intense compared with the person’s conscious intentions.
Why It Matters
Understanding sensitisation shifts the narrative from “you must secretly still love it” to “your brain’s wanting circuits were over‑trained” — a more accurate, less shame‑soaked way to think about persistent cravings.
Closing Line
Sensitisation is the brain’s over‑learning of “this mattered,” echoing that message loudly even after the pleasure and logic have left the room.